Sheet metal repair with automotive panel bonding adhesives

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bsmtfullofsuds

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Aug 25, 2006
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In the automotive industry, new adhesives are being substituted for welding to attach non-structural sheet metal on new cars at the factory, and also in the body shop. Typical uses are door skins, quarter panels. Testing by stretching and crash tests shows the metal fails before the adhesive bond. The adhesive coating inhibits corrosion and unlike welding, there is no heat to warp the panel. DIY'ers without welding gear now have an alternative to Bondo for rust repairs.

Perhaps useful on appliances too? I am curious whether it will withstand hot water and detergent, so a rustout in a washer or dishwasher tub can be ground out to good metal, and sheet metal patch glued on.

Costs about $100 to get started, $30 for a cartridge of 3M Automix 8115 plus $70 for the special dual-plunger applicator gun. Other brands Lord Fusor and Duramix exist, each have their own guns.

 
Which reminds me

There was a thread a few months back, I don't remember in
which forum, where Robert had a "nightmare" repair of rust
in a tub (or outside a tub where supports attached.) He
was going to describe how he did it, but I don't remember
that he ever did. Did I miss it?

Robert??????????

Would like to see the crash test results/pictures.

But (I) certainly have to give credit to 3M (being in
Minnesota) for all the wonderful things they have created.
(Too bad about Scotchguard though.)
 
Well, JB Weld is the traditional way to repair metals subject to heat and light stress that you don't want to weld. Years ago I fabricated and attached a bit of 1/8" Aluminum sheet to repair a cracked motorcycle block - the area around the ignition pickup on the side. The JBWeld has held for many years without any sign of weakening. Granted it's not a stressed area, and it's not subjected to oil or water, but it does see a fair amount of heat with no problem.

I am planning on fixing the tub on my '65 Whirlpool washer with JBWeld. I may not even include any metal in the repair, as the hole is rather small. I trust the stuff will hold up to hot water and detergent quite well. Heck, my house is held down to the foundation using 1/2" studs that are glued in place with an epoxy glue very much like JB Weld.
 
Hmmm. Perhaps the trick with JB Weld, as well as with most epoxies, is to make sure the parts to be joined are perfectly clean, with no trace of oil or grease. A spray of brake clean or acetone will generally do that for a metal part. Next, the proportions of resin to hardener should be equal, or as equal as you can get. Then, they have to be mixed thoroughly. If you feel the back of the cardboard or paper you're mixing them on, it should feel a bit warm. Then the parts must be joined and left to cure for as long as the packaging says. There are some quick drying ones, but I sort of prefer the slow curing type. Finally, JB Weld is not a substitute for strong metal or even plastic. It is somewhat brittle, and can't take a lot of shock. Even so, something very similar (I use Simpson Strong-Tie epoxy) approved, if not preferred, for fixing foundation bolts. If done right, these are less prone to failure than wedge type anchors, which tend to spall the concrete, causing stud failure.
 
"Even so, something very similar (I use Simpson Strong-Tie epoxy) approved, if not preferred, for fixing foundation bolts. If done right, these are less prone to failure than wedge type anchors, which tend to spall the concrete, causing stud failure."

Can I get a little more explanation of terms/phrases?

"fixing foundation bolts" (does that mean repairing or
attaching/affixing?)

"wedge type anchors" (as related to either foundations or bolts)

"stud failure" (vs. plate failure?)

Thanks.
 
"fixing foundation bolts" (does that mean repairing or
attaching/affixing?)

It means attaching. First you drill a 5/8" dia hole. Then you carefully brush and blow all the dust out of the hole. Any dust might interfere with the epoxy. Then you squirt in epoxy from a specially made dual cannister with a "mixing nozzle". Plunge in the stud and then wait overnight for it to cure and it will be a very strong bond - as if you'd inserted the stud into the foundation concrete when it was first poured.

"wedge type anchors" (as related to either foundations or bolts)

Wedge type anchors (I forget the name on the box) are basically soft metal nuts that you put on the end of the stud, then put the stud with the nut end down into the hole. Then you turn the stud and it expands the wedge anchor at the bottom of the hole, locking it and the stud into place in the hole. The problem is that the force is exerted on the concrete just at the bottom of the hole, concentrated in a small area. When a large force hits the concrete around the wedge nut anchor may fail (spall) and then the stud will be able to be pulled out and the house may slide off the foundation.

"stud failure" (vs. plate failure?) See above.
 
Okay - I see - studs are "bolts" not wooden studs and the whole
purpose is to create sturdy bolts/studs/anchors to attach the
sole plate to. Using the epoxy/drilling sounds like it would
create a more accurate placement (if it makes a difference),
but a lot more work. Though I would think a bolt (with an
L-shaped head) would be stronger than the epoxy, but may not
make a significant difference if forces are strong enough to
damage one or the other, then the rest of the structure is
probably already gone.
 
Well, yes, an L-shaped stud/bolt would be just fine, but it must be inserted into the wet concrete when the foundation is poured. The epoxy and wedge anchors are used for retrofitting older foundations to modern seismic reinforcement standards. And yes, one can place the retrofit anchors somewhat more precisely, I suppose, than the original ones, which I suppose can be a little tricky as one must measure where they go so they don't interfere with a wall stud position (although it's easy enough just to cut one off with a reciprocating saw).

A little tricky was drilling through the sill plate first and then the concrete. The masonry drill bit doesn't really like to cut wood, but it will do it with a bit of tearing. I used a rotary hammer to drill through the concrete, and it was pretty easy but very dusty and noisy. I made a little attachment for a midget shop vac (1.5 gallon) hose that allowed me to shoot compressed air into the hole and vacuum up the concrete dust at the same time. Then I used a bottle brush to clean the hole and blew/vacuumed it again. Everything passed inspection with flying colors - the inspector puts some torque on a few random bolts and if the studs stay put then it passes. It is exhausting work, however, in a crawl space. There were a lot of places where I had to worm my way horizontally to get around. This was made more difficult by the broken/hardened clay soil under the house. Kind of like body surfing on 3" dia rocks. At the end of the retrofit (I think it took me a couple weeks full time), I had black/blue bruises all over. After that I covered the entire clay crawl with 10 mil plastic sheeting, which makes it a lot easier and cleaner to slide around down there, lol. And I will return there several times more; first to finish putting insulation under the flooring, then to run some speaker/antenna cabling for the living room/home theatre, and then at some point, to replace the galvanized steel plumbing with copper.

Looking for volunteers ;-)
 
I'd volunteer, but...

A bit too far to go. ;)

Do you still have your compressed air/vac
attachment you could take a picture of?
 
Studs are usually wood, but it doesn't matter for this discussion. What Suds is saying is that the mechanical act of installing the wedge anchor bolt creates the potential for very strong loading in a small area, and this may fracture the concrete in the foundation. Remember that concrete has very high compressive strength but very poor tensile strength. If anchor bolts are installed before the concrete is poured, then they have metal plates on the ends or special shapes that allow the loads to be distributed more evenly to the concrete. This is usually stronger than using the epoxy after the fact, but there will always be cases where a bolt is needed in already existing conrete, and the epoxy is an acceptable solution. As Suds pointed out, it takes some skill and knowledge (not to mention a little pride in one's workmanship) to do this job correctly and ensure the epoxy can work to its maximum potential.
 
Studs are usually wood

The term "stud" has many meanings, but it's debatable that a stud is usually wood. Stud is a very common term in the automotive world to refer to a threaded rod, quite often with different threads on either end. One end is inserted into a block or head, the other is left exposed so that other parts can be attached with nuts holding them in place on the stud. Of course there are other common uses for the word stud, including some that might make some here blush a little.

I just checked a box of studs. Simpson Strongtie refers to them as "Threaded rod anchors for use with epoxy". I also checked a box of what I've been calling "wedge anchors". They are more commonly referred to as "expansion bolts", although they are really "expansion nuts". The box is Diamond brand, Red Seal "Calking [not caulking] Anchors". You drill a 3/4" hole, drop in the anchor right side up, tap it in place with a special tool, and then screw in a 3/8" bolt (or threaded rod/stud) to affix whatever to the concrete. I also have a tray of assorted expansion bolts and setters that is hand labeled "Tapens and setters". So I suppose "Tapens" or "Tapins" are also used to describe these expansion bolts.

I'll try to snap some photos when I get more down time. Maybe one of the "Suck'n Blow" gadget I made for cleaning out the bore holes. Although I did think at one time it might be something I could try to patent...
 
epoxies and loads

This is one of the best threads in a long time! Thank you, Rich, so much!
When we redid the safety railings on the balconies and terraces in our building a few years back, the city forbade expansion bolts. The chance of causing damage and catastrophic failure was too great (German safety standards tend to see things from the 'the glass is half-full, it's slippery and has a crack anyway...' perspective.
So they were anchored using the same technology Sudsmaster applied. Took awhile, but every single stud set (oh, I just love these terms...bet the PC crowd is just dying over this thread) passed the torque test and the angle measurements standing proud and straight.
Recently, I saw a single cartridge solution using a mesh wrapped anchor-plug (Dübel) which claimed to meet the same standards as traditional methods, but priced so it made sense for DIY'ers. Anyone have any experience with it?
 
and Basement full of Suds, too!

I overlooked who started the link...thanks to you, too. I am so curious about this technology...yup, have a job of work to do coming up which might involve it.
By the by, some JP Weld parts I cast several years ago are still working perfectly in my folk's house. They are subject to heavy static loading, but no sheer stress...replaced the latches which hold a storm window 'up' in a store-able screen door, stuff like that.
 
Well, thanks Panthera, and I agree that some if not most credit needs to go to Basmtfullofsuds for starting the discussion in the first place.

Re: German building standards. Interesting. When I did the foundation retrofit, I was flummoxed by the fact that the rotary hammer drill was too tall to sink the holes perfectly vertical. The inspector came by and helped a lot by saying it would be just fine to slant the drill slightly, so that I could use the space between the floor joists just outside the plane of the cripple wall. That worked just fine.

Haven't heard of the mesh/expansion bolt product, but then I haven't been looking for such products since about 2000 when I did my own foundation retrofit. I still have a couple of boxes of 7" foundation bolts... which I might use on the garage and workshop. They are on slabs and have some bolting but more probably wouldn't hurt.

Regarding the foundation bolts... most people realize the main goal is to prevent the walls from sliding off the foundation. But another purpose is to prevent the structure from pulling up from the foundation. This can happen when the shaking is sufficient to make the building sway back and forth, causing it to want to lift up at one end and then the other. For this reason the retrofit project also included securing the wall studs to the sill plate via plywood paneling, and also securing the first floor wall to the cripple wall via nailed-in steel plates and angles.
 

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